The barges burned all night, observed by crews on the scene, because the scene was "too unstable."

"We'll just let the product burn off and then it'll put itself out when the fuel is gone. Then we'll go in and make sure everything's OK," Mobile Fire and Rescue Chief Steve Dean told Mobile news affiliate WPMI.

Thursday morning, with the fire out, Fireboat Phoenix moved toward barges to make sure mooring lines were secured.

Raw gasoline, without additives, was involved in the blaze, according to the Mobile Fire and Rescue.

The cause of the blast is currently unknown, but the Coast Guard is on the scene investigating.

Fox 10 reports that the explosions occurred near Austal, an Australian company that specializes in the design and construction of aluminum vessels. Their facility is located between the tunnels and the waterways near downtown Mobile. Some of the employees at Austal were evacuated.

Lt. Mike Clausen of the Mobile Fire and Rescue told Fox 10 that there was a three-mile flight restriction and a mile-radius evacuation area around the scene of the blast. However, the I-10 Bayway and both tunnels remained open.

He also said it was not known how much gas the barge was carrying at the time of the blast.

Residents in nearby Spanish Fort, 10 miles from Mobile, and in Citronelle, 30 miles away, reported hearing the explosion.

Terry Wilhite, who lives in Spanish Fort, drove to the scene when he heard the explosion.

"It's hard to see, but the smell is strong and it's definitely the smell of burning fuel. There are lots of fumes in the air. We noticed as soon as we crossed the causeway a striking smell of burning gas," he said.

He was sitting at home when he heard the first blast.

"It shook the house. It was outrageous. It was one heck of a big explosion," he said.

The Carnival Triumph, which was towed into Mobile two months ago after it became disabled at sea, was undergoing repairs there. It was not in danger.